Ultraviolet instrument lamp



July 1, 1941. J. M. ROPER ULTRAVIOLET INSTRUMENT LAMP Filed oct. s, 1940 :El-Ej m n .NIR E. O. MM m J. m

Patented July l, 194i uNirEu STATES PATENr orrics 2,247,409 l UL'rnAvIoLE'r INSTRUMENT LAMr John M. Roper, Washington, D. C.

Application october s, 1940, serial No. 360,439

z claims. (ci. irci) (Granted under.. the act ol` March'li, 1.883,l as

amended Aprilll, 1928; 37u (D. G. '257) A further object of this invention isvto provide Aan ultraviolet instrument lamp which is incandescent in character and doesnot need the presence of any mercuryor other -vapor or gas to provide the necessary quantity of ultraviolet light.`

Still a further object of this invention is-to provide an ultraviolet instrument lamp which is light in weight, and thus (does not appreciably add to the amount of weight to be carried by the vehicle, additional weight being critical in both heavier than and lighter, than air vehicles, it being realized that there are aconsiderable number of instruments used on air vehicles, and although the diierence in Weight houette the outline of the instrument, is likewise transmitted thereto.

Still a further object of this invention is to provide an ultraviolet instrument lamp wherein the lamp is provided with an external reflecting surface about a portion 'of the bulb so as to concentrate and control the direction of the ultraviolet light to the desired area only, the ultraviolet light being produced by an incandescent filament operating through a lamp bulb made of any of thewell known ultraviolet transmitting glasses, such as Corex glass, or other special glasses known to the trade, whereby the reflected portion of the light from the nlament passes through three thicknesses of ultraviolet transmitting glass, thereby substantially eliminating all visible light therefrom, while the direct rays from the lament pass through but a single thickness of transmitting glass, thereby including a very faint portion of visible light therewith. l

Afurther object of this inventionis to pro-` vide an incandescent vfilament ultraviolet lamp' which can be utilized in the conventional power system 'of an airplane vehicle and ldoes not cause 'any more current drain thereon than any ordinary instrument'lamp of similar voltage, as contrasted'with the gas type ofI `ultraviolet lamps, such as exemplified, for instance, in U. S. patent to Zecher, 1,951,116.

While this light is intended forcuse in conjunction with instruments such as usually form part of the instrument board, it will be undery stood that the term instrument' also `.includes control members, maps, or `any other parts of 4the `vehicle used in conjunction withthe operation ofthe vehicle that may have portions painted or printed with ultraviolet activated or other glasses known to the trade.

kWith the foregoing and other objects in view, the invention consists in the construction. combination and arrangement of parts hereinafter described `and illustrated in the drawing, in

which: I

Fig. l is a sectional view through one form of ultraviolet lamp of `,this invention;l

Fig. 2 i-s a sectional view on line 2--2 of Fig. l, showing the path of the light;

Fig. 3 is a fragmentary view showing the lamp of Fig. 1 in operative position;

Fig. fl is a partly sectional view of another form of lamp; and

Fig. 5 shows the lamp of Fig. 4 in operative position.

'There is shown at Ill the instrument lamp of this invention, consisting of a. conventionalbase I I through which extends the customary electrode leading to the incandescent filament I2, which, it will be observed in Figs. 1 and 2, is mounted off-,center from the lamp bulb I 3, in a manner similar" to that shown in U. S. patentto Biggs, 2,158,561. In this case the lamp bulb I3 is made of ultraviolet transmitting glass such as Corex, In order that such glass may lter out substantially all of the visible light and transmit only ultraviolet light, the glass must be of a fixed thickness, usually from l/s" to f/w" of an inch. The glass I3 of this lamp, however, will be only one-third 'of this necessary thickness, as a. result of which one portion I4 of the glass will transmit a, faint amount of visible light therethrough from the rays i9 coming directly from the incandescent iil-ament I 2. Another portion I5 of the lamp bulb I3 is exteriorly coated at I6 with a suitablereecting material such as silver, nickel, chromium or other suitable reflecting material, which, if desired, may have a protective coating I1 thereover to prevent the reilecting material from being marred.

Light rays I 9' coming from the incandescent filament I2 travelling tothe portion I5 travelsV through this portion I to the reecting surface of the material I6, and then are reflected back through vthis portion I5 and then through portion I4 in the desired direction to the faces I8 of the instruments 20, when"the lamp III is' mounted in a suitable bracket as at 2|. IThe faint por-tion of visible light coming directly from the filament I2 as at I9, may be suilicient to silhouette the outlines of the instruments 20 without, however, providing any substantial amount of visibility thereto.

The reilected light rays from the portion I5 thus pass through three thicknesses of ultraviolet illtering glass, while the direct rays pass through a single lthickness .of filtering glass, thus providing suiiicient ultraviolet light to make the indications on the faces I8 of instruments 20 clearly visible to the operator without allowing any substantial amount of visible light to reach the instruments faces, and thus interfere with the operators visual abilities.

As thus constructed, the incandescent lament I2 is of such low voltage that it does not lcause any appreciable current drain on the vehiclepowtions and arrangement of the parts may be made by those skilled in the art without departing from the nature of the invention, within the scope of what is hereinafter claimed'.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what ls claimed is:

l. A non-gaseous ultraviolet lamp comprising a filament, a. lamp bulb of ultraviolet transmitting and visible light absorbing properties, said bulb being of a thickness to substantially absorb the greater portion of but not all of the visible light from the illament,and av reiecting surface externally coated over only a portion of said lamp bulb to renect the u1trav1o1et light and direct the remaining light ina desired direction only through theemaining uncoated portion, whereby the reflected light passes through three thicknesses of ultraviolet transmitting bulb to absorb substantially all of the visible light thereof and the direct light passes through a single thickness of the bulb to include a small-portion of visible light therewith.

2. An incandescent ultraviolet lamp comprisrlng an incandescent lament, a lamp bulb of er system, thus eliminating the necessity of aduncoated, while the top portion 26 is provided with an external refiecting coating 21 and pos. sibly a. reflecting material protective coating 28. In this case the lamp is mounted in the bracket l0 extending through theinstrument board 3l in which are mounted the instruments 32.

Other modifications and changes in the proporultraviolet transmitting and visible light absorbing properties, said bulb being of a thickness to vsubstantially absorb the greater portion of but not all of the visible light from the incandescent iilament, and a reilecting surface externally coated over only a portion of said lamp bulb to reflect the ultraviolet light and direct the remaining light in a desired direction only through the remaining uncoated portion, whereby the re 

